Drop-in replacement for lead acid batteries, and more bang for your buck. Maintenance-free, modular, and lightweight. Holds a charge for up to 1 year without a load, and no need for a trickle charger. Can be wired in series up to 48V and unlimited in parallel. Built-in Battery Management System (BMS) protects the cells against excessively high or low voltages, high currents, short circuits, and excessive heat or cold. Automatic cell balancing (by the BMS) which reduces the charging rate in cells that have been topped off first, letting the rest of the cells catch up. This ensures that the cells are always in balance, and maintains the quality and efficiency of the battery.